/Engine/Plugins/Runtime/OptionalMobileFeaturesBPLibrary/Source/OptionalMobileFeaturesBPLibrary/Classes/OptionalMobileFeaturesBPLibrary.h
Returns if headphones are plugged into the device
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category="Mobile") static bool AreHeadphonesPluggedIn()